[U-Boot] loadb problem. Hangs on START_CHAR

bomellberg bo.mellberg at physio-control.com
Fri Nov 7 13:53:22 CET 2014


Hi.

I'm working on getting u-boot running on a custom board. I am using code
from Emcraft as a starting point. The cpu is NXP LPC4337. The board has
external SDRAM and SPIFI flash, but no wired network.

I can boot u-boot fine, and I can perform some memory operations with md and
mw.

I can load the Hello World standalone example using loads and run it with
go.

I cannot use the loadb command though. The transfer hangs at the beginning.
Using some crude printing debugging I found that the START_CHAR is not
received.

>From cmd_load.c:



I never get the "S", so the transfer never starts. I have tried Tera Term on
Windows and C-Kermit on Linux, using the settings mentioned in the DULG. I
have tried two different USB-to-RS232-3.3V dongles.

A search in the archives shows a possible explanation in FIFO byte order,
but I cannot find a place to alter this. Could it be the FIFO byte order for
the UART is important for the kermit transfer, but not for the console?

An oscilloscope picture of the kermit transfer's first bytes:
<http://u-boot.10912.n7.nabble.com/file/n195144/tek00002.png> 
It sure looks like a 0x01 as the first byte. But the code doesn't reach the
"S" debug.

If I send 0x01 using RealTerm, I get the "S" debug. I can't figure this out.

Thankful for any help.

/Bo



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